Parallel Inverter Transition Control Without High-Speed Synchronization
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Solution Overview
Problem
Systems of machines connected in parallel for energy storage and grid interaction require high-speed communications for synchronization between master and slave machines during mode transitions, leading to increased hardware costs and potential circulating currents.
Innovation Solution
The system configures master and slave machines to switch between current source and voltage source modes based on voltage amplitude and phase, allowing the slave machine to synchronize directly with the master machine's voltage without high-speed communications, eliminating the need for electrical parameter sharing and preventing circulating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-speed communications are used for master-slave machine interaction, then synchronization during mode transition is improved, but hardware cost increases due to indispensable communication bus
Solution Approach 1:
The patent extracts and eliminates the communication bus from the system by implementing direct voltage sensing between master and slave machines. The slave machine senses voltage directly from the master machine's output terminals, removing the need for separate high-speed communication hardware while maintaining synchronization capability.
Solution Approach 2:
The voltage output terminals of the master machine serve dual functions: both as power output terminals and as sensing terminals for the slave machine. This multi-functionality eliminates the need for dedicated communication buses, reducing hardware complexity while maintaining synchronization.
2Measurement precision
If high-speed communications are implemented for parameter sharing, then synchronization precision is improved, but circulating current risk increases
Solution Approach 1:
The patent removes the communication bus that could potentially cause circulating currents by implementing direct voltage sensing. The slave machine senses voltage directly from the master machine's output terminals, eliminating the communication pathway that might introduce harmful circulating currents while maintaining parameter synchronization precision.
3Device complexity
If voltage sensing is implemented without high-speed communications, then hardware cost is reduced, but synchronization speed may be affected
Solution Approach 1:
The patent replaces the electronic communication bus system with direct electrical voltage sensing. The slave machine senses voltage directly from the master machine's output terminals through electrical connection, achieving synchronization without the need for high-speed communication hardware while maintaining response speed.
Data Source
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AI summary
A system of machines connected in parallel and a method for controlling transition between an on-grid mode and an off-grid mode are provided. A master machine and a slave machine each are an inverter or a power converter. On-grid ports of the master machine and the slave machine are connected to a grid. Off-grid ports of the master machine and the slave machine are connected, for supplying a load. In transition from the on-grid mode to the off-grid mode, the master machine switches from a current source mode to a voltage source mode based on amplitude and phase of voltage with which the system is off a gird, and the slave machine senses voltage at the off-grid port of the slave machine in amplitude and phase, and switches from the current source mode to the voltage source mode based on the sensed voltage. No highspeed communications involved in the transition.